Melin-y-Plas is a 3-storey building of four bays, with single-storey lean-to on the north-west elevation. Its large rectangular windows suggest a mid-19th century date. In 1975 the main building was rendered, with a slate roof. The brick-walled mill pond was supplied by a leat from the Afon Caradog, and the tail race passed under a northward loop of the river to reach a sufficiently low discharge point. In 1975 a wooden launder was still in situ, but the large overshot wheel and internal machinery had been removed, though four bedstones remained in situ.
In June 2007 the building was in process of conversion to dwellings. In November 2008 it was being marketed as two semi-detached dwellings. Vehicle access and parking had been constructed within the millpond, breaching its brick wall but leaving most of it, with the bypass sluice, intact. The position of the waterwheel axle hole is marked by a square indentation in the north gable.
W J Crompton, RCAHMW, 19 November 2008.